Other explanatory variables

In addition to the oceanographic variables derived from MODIS satellite data, we used geographic and observation-level variables to help explain the sonar backscatter data (Table 1). Geographic variables included distance from shore, and ocean depth derived from the general bathymetric chart of the ocean (GEBCO) 2014 30 arc-second grid bathymetry dataset [31]. Observation variables include characteristics associated with the sonar data collection, namely a binary indicator for whether the data were collected during the day or night, and categorical indicators for wavelength, depth bin, and wavelength-depth bin combinations.

For each variable, we list its name, type, source, and whether it was included in the reduced model. The full model includes all explanatory variables.